Wednesday, November 11, 2009

Tuesday, October 20, 2009

... you may be in for a big surprise at just how many wallabies are out there.

As part of the Alternatives to 1080 Program we are monitoring animal numbers on a pasture area north of Launceston using a thermal imaging scope to get a feel for animal numbers at the site. Below is some footage which shows the numbers in two paddocks. In total I counted 67 wallabies (and also cattle) in the lower paddock, and 136 in the upper 2 paddocks last night.

I counted just over 210 in the upper 2 paddocks the previous night, but I did that count at about 9pm, and did this count at closer to midnight (the date and time on the video footage is incorrect) so I suspect more of the animals had moved down into the lower paddock explaining the difference in numbers.

Anyway, the video is more to give you a feel for the sort of 'intelligence' that the thermal scope can give you - you can see both its strengths (easy ability to locate animals at large distances without alerting animals to your presence) and weaknesses (unless the animal is moving or within 100metres it's almost impossible to identify species).

As an aside after counting the animals in the lower paddock, i walked up to the top paddocks via a different route and circled back down onto it from above and did a count with a spotlight. I was only able to count about 10 wallabies, and I could hear the rest of them running away into the bush.

Lower Paddock, approx 11:10pm, 21 October 2009. You can see how easy it is to find an animals location, but also you have no way of identifying species at these distances.

The next three videos below are actually panning across the same paddock from left to right, but unfortunately the video recorder I am using also breaks the images up into quite small segments. This is one of two top paddocks.

Top Paddock A (1 of 3), 21 October 2009.

Top Paddock A(2 of 3), 21 October 2009.

Top Paddock A (3 of 3), 21 October 2009.

I've just included the final video below, because although still not that clear on the footage, when looking through the scope at night at these distances (about 100metres), it is quite possible to distinguish between wallabies, possums and wombats, but not within species of wallabies.

Thursday, September 10, 2009

Deer aren't a headline browser in Tasmania, and yet within their range they can be a significant problem for plantation managers.

Fallow deer appear to be attracted to the seedling stockings used to control browsing damage from other species, often pulling them, and the seedlings they are meant to be protecting, out of the ground.

We're not sure whether the deer are just attracted to the stockings, or whether they are trying to eat the seedlings, although it is not uncommon to find seedling stockings in the guts of deer, indicating that they do at least eat some of the stockings.

The Alternatives to 1080 Program stumbled across a New Zealand Game Control company called Epro some months ago which has developed a deer repellent they use to stop deer eating 1080 baits, and the idea formed that if it is effective, maybe their repellent could be used on stockings to reduce the impact of deer.

Epro were contacted, and interested in the idea of trialing their product to protect seedlings from deer browsing, and so a couple of their staff came over to Tasmania in the first week of September to see the problem first hand and to see if their repellent might have some application.

With thanks to John Bennett of Gunns Limited, we visited some plantations south of Cressy to have a look at the problem, and to set up a small trial to see if we could actually apply the repellent to the seedlings and the stockings.

On a somewhat overcast day on the 2nd September, we mixed up a batch of their repellent (which is non toxic, as I can personally verify having tasted it) and we coated two areas of seedlings which both had evidence of signficant deer movement through them.The main purpose of this little trial was to see if the repellent would actually "stick" to the seedlings and stocking material, and whether it could be painted or sprayed on, and the initial signs have been very positive.

We were able to both spray and paint the repellent onto seedlings in the field quite quickly and easily, though the cheapo sprayers we used did clog up eventually due to the sticky nature of the repellent.

What's even more positive is that after several days of quite heavy rain, a return to the site on the 8th of September showed that the repellent had survived the rain extremely well, and there was no browsing damage yet ... but then a walk around the larger plantation found no other browsing damage elsewhere either.

Other Species Effectiveness?

We already know that Epro's Deer Repellent doesn't repel brushtail possums as it was specifically designed this way (it's purpose r was to be used on 1080 bait aimed at killing brushtail possums), but we weren't so sure whether it might repel wallabies or not, so we decided to set up a short trial to see how wallabies would react to it.

To do this, we coated a pile of carrots in the repellent and put this pile in front of a camera in the wallaby pen at Prospect which is a population of wild bennett's and rufous wallabies. These wallabies are used to being fed carrot as a bit of a treat, so we fully expected the carrot pile to be gone the next day ... but when we came back it wasn't, in fact nearly 2 weeks after the initial carrot pile was put out, it remains largely untouched, and we expect most of the browsing is due to possums (which were recorded in the first few nights browsing the pile).

Video footage (of which some extracts are below) show typical responses of wallabies coming to the bait pile on the first night:

Somewhat intrigued by this unexpected result, we set up a second trial a week later in the same pen, but this time we put out two piles about 5 metres apart, each with 5 kgs of chopped up carrots, but one was again coated in the repellent, and the other was a control pile, just to make sure that other variables like alternative food availability weren't stopping the wallabies eating the green carrots.

As can be seen in the two videos below, the first wallaby was eating carrots off the uncontrolled pile within hours of it being put out, and well the second video just speaks for itself. Those wallabies like their carrots.

What is most interesting about this trial is that after 3 days, the control pile of carrots was all gone, but other than about 6 pieces of carrots which have been partially nibbled, the treated pile is pretty much untouched. This is a fascinating result, demonstrating the potential short term effectiveness of this repellent against wallabies.

I was in fact so intrigued by this outcome, and having been assured that the repellent is completely safe, I sampled one of the treated carrots that had been out for a week just to see if I could see what was repelling the animals. For me, there was no real smell or taste difference to a normal carrot, so one of my next thoughts is to just try a green dyed placebo to see if it has the same affect as the repellent.

So that's where we are at today. We will continue to monitor both our carrot piles and the seedlings out on the coupe to see how things are going, and if the results continue to look positive may further investigate this repellent with Epro in the coming months.

Some caveats on all this, include that (1) the repellent is fairly expensive and currently Epro do not sell or use second parties to distribute or use it, so there are some restrictions there, and (2) we still don't know it's effectiveness beyond a few weeks, where we need something that will work for at least a few months, however it's always good to get a trial like this off on the right foot like this one has.

Friday, July 17, 2009

Whilst wandering around a pet shop up on the Gold Coast last week I stumbled across a cool repellent device: Contech's Scarecrow.

It's essentially a motion-based sprinkler system that (according to the manufacturer) detects animal movement in a 110 degree arc in front of it and then shots out a 2-3 second burst of water from an integrated sprinkler. The combined noise, movement and water spray is supposed to startle the animal and scare it away. The range is only about 10 metres, but the concept is pretty exciting.

I should probably note that I have also subsequently found that at least one other similar product from another manufacturer.

It cost $129 to buy, but I have seen it on Australian websites for between $108 and $129.

I was so interested in this because, the failure of many of the repellents and deterrents we (and others) have tried to date such as gun shot noises, flashing lights, other predator odours is partly I believe because of the co-evolution aspect where the animals learn that the repellent isn't actually a threat so quickly learn to ignore them.

I have been playing with the idea of an automated Sentry system based on a paintball gun mounted to a detection system after stumbling across The Sentry Project a few months ago, but this approach was foiled by the fact that the Patriot act prevents the export of the software out of the U.S.A. plus there was also operational problems with potential injury to animals, and technically how to get the movement recognition to work at night. Finally, with a maximum range of 50 metres (the effective range of a paintball gun) and requiring a laptop, lighting system and paintball gun for every sentry they would be quite expensive, highly prone to theft, and therefore of fairly limited application.

The sprinkler system though is a much more viable system (and less problem with potential eye injury to animals) for smaller areas requiring protection.

So, I bought one, tested my baggage limit in bringing it back to Tassie, and handed it over to Mick Statham and his team to trial in their wallaby enclosure at Mt Pleasant, Launceston.

Trial Day 1 (Thursday 16th July, 2009)

The Scarecrow was set up in the wallaby enclosure with a pile of juicy carrots placed about 2 or 3 metres in front of it. The spot had been fed with carrots the previous day, so the wallabies (both Bennetts and Rufous) already knew there was food there and had cleaned the initial carrots away. I should say the enclosure is about 0.8ha, with a I think 10-15 bennetts and rufous wallabies in it. They have plenty of other food in the enclosure (just look at the grass in the videos) and are fairly free roaming.

Initial results were very positive. Even before Mick had left the site, both a rufous and bennetts wallaby had approach the carrot pile and been promptly scared off by the Scarecrow. Have a look at the video below:

However it was only hours before the effectiveness began to dissipate :

... and ultimately the scarecrow's success was pretty short lived: by 5pm that night footage showed several bennetts wallabies happily munching on the carrot pile as the sprinkler went off over their heads. Later footage showed both rufous and bennetts wallabies demolishing the carrots as well, chasing each other and seemingly genuinely unconcerned by the scarecrow (see video below which is two x 1 minute videos spliced together)

So, day 1 wasn't the smashing success we hoped for, but all is not lost, it could be that because we'd set the sprinkler up high to maximise its range, that the wallabies learnt to run under it and then they could eat in peace. Once one wallaby did this, the others would quickly have followed. So Plan B is to lower the water so it shoots directly at the wallabies ... stay tuned ...